A FAINT-GALAXY PHOTOMETRY AND IMAGE-ANALYSIS SYSTEM

An interactive image-analysis system containing general facilities for image manipulation and picture arithmetic is described. The main purpose of the system is to perform photometric analysis of direct images of galaxies. The program includes a faint-galaxy photometry algorithm which performs automatic object finding, classification, and total-magnitude photometry for galaxies with provision for moderately crowded fields. Photometry and object classification are performed by analyzing the growth curves of each object after its neighbors have been masked out. Also available is a simulation routine for creating realistic artificial CCD images of fields of stars and galaxies. The simulation algorithm takes into account the observed galaxy and star counts, cosmological models, properties of galaxies, observing conditions, and detector characteristics. The performance, reliability, and limitations of the faint-galaxy photometry algorithm are tested using these simulated images.